Retainer for roller bearing

ABSTRACT

An end portion of a pin  2  rotatably supporting a rolling body  1  is fitted in a pin-receiving hole  4  formed in an annular side plate  3 . The pin-receiving hole  4  has interference in a range from 5 to 40 μm between itself and the outer diameter of the pin  2 . The end portion of the pin  2  pressed in the pin-receiving hole  4  with 5-40 μm interference is welded to the annular side plate  3.

TECHNICAL FIELD

The present invention concerns a cage for use in a roller bearing suchas a cylindrical roller bearing or a tapered roller bearing and,particularly, it relates to a cage for use in a roller bearing referredto as a pin-type.

BACKGROUND ART

In a rolling bearing used, for example, in a speed retarder of a rollingmill or a press machine, since abrupt fluctuation of load occursrepetitively in the radial direction, rolling elements formed in acylindrical or conical shape are used as rolling elements assembledbetween an outer bearing ring and an inner bearing ring. A cage forretaining rolling elements of such rolling bearings (hereinafterreferred to as a “roller bearing”) includes various types and thosereferred to as a pin-type cage are constituted such that one ends ofpins inserted through the central hole of a roller (rolling element) isfitted into pin-receiving holes formed in one annular side plate of apair of annular side plates opposed to each other while putting theroller therebetween, and the annular side plate and the pins are weldedso as to cover the entire end faces of the pins that are fitting intothe pin-receiving holes as disclosed, for example, in JP60-182525U orJP11-325063A.

However, in the pin-type cage described above, as shown in FIG. 49,since the hole diameter of the pin-receiving hole 4 is larger than theouter diameter of the end of the pin 2, a gap g is formed between thepin-receiving hole 4 formed in the annular side plate 3 and the pin.Therefore, when a load in the radial direction is applied on the pin 2,stress concentration occurs to a weld portion 6 for the pin 2 and theannular side plate 3 to possibly cause fracture such as cracking due tostress concentration caused to the weld portion 6.

Further, in the existent pin-type cage, since the annular side plate 3and the pin 2 are welded so as to cover the entire end face of the pin 2fitting into the pin-receiving hole 4 in order to prevent cracking orthe like in the weld portion due to stress concentration, a residualtensile stress is generated to the weld portion 6 for the pin 2 and theannular side plate 3 to result in a problem of lowering the strength.

Further, in the pin-type cage described in JP11-325063A, when a rollingelement moves largely toward the annular side plate and is in contactwith the pin, it may be sometimes in contact with a portion with nosurface hardening layer or a portion where the depth of the surfacehardening layer is shallow. Further, at the pin surface where thesurface hardening layer is not formed, the mechanical strength to thebending stress is also low in addition to the wear resistance, comparedwith a portion where the surface hardening layer is formed.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a cage for use in apin-type roller bearing excellent in mechanical strength by suppressingconcentration of stress to a weld portion for a pin and an annular sideplate.

A cage for use in a roller bearing according the first inventioncomprises a plurality of pins for rotatably supporting rolling elementsof a roller bearing and a pair of annular side plates for retaining, byway of the pins, the rolling elements each at an equal distance in thecircumferential direction of a bearing ring, in which pin-receiving holefor fitting with one ends of the pins are formed to at least one annularside plate in the pair of annular side plates, wherein fitting betweenthe pins and the pin-receiving holes is applied as interference fit for5 μm or more.

In the cage for use in the roller bearing according to the firstinvention, fitting between the pins and the pin-receiving holes ispreferably interference fit for 5 μm or more and 40 μm or less. Further,it is preferred that the ends of the pins fitting into the pin-receivingholes are welded to the annular side plate, the annular side plate hasweld portions for the pins and the annular side plate at the outerlateral surface, and the weld portions are formed into a ring shapesubstantially at constant width. In this case, the weld portions arepreferably formed by TIG welding or plasma welding for the pins and theannular side plate. Further, it is desirable that the extension amountof the weld portions of the annular side plate relative to the outerlateral surface thereof is within 0.5 mm.

Further, in the cage for use in the roller bearing according to thefirst invention, the ends of the pins fitting into the pin-receivingholes are preferably finished by grinding and, further, thepin-receiving holes have a surface roughness, preferably, of 1.2 μm orless. Further, the ends of the pins fitting into the pin-receiving holesmay be applied with surface fabrication by a method such as barrelfabrication, honing fabrication or electrolytic polishing.

Further, in the cage for use in the roller bearing according to thefirst invention, the pin-receiving holes may be formed in both of thepair of annular side plates. In this case, one of the two ends of thepin is preferably formed to a smaller diameter than that of the otherend.

Further, it is preferred that the pins have a shaft portion passingthrough a rolling element insertion hole formed in the axial core of therolling element and the two ends of the pins fitting into thepin-receiving holes are formed to a larger diameter than that of theshaft portion. In this case, the pins may have a chamfered portion atthe top end face thereof, and the angle of inclination at the chamferedportion is preferably 30° or less relative to the outer circumferentialsurface of the pin. In this case, the chamfered portion is preferablyformed into an arcuate shape along the axial direction of the pin.

Further, the pin-receiving holes preferably have a chamfered portion atthe inner surface of the annular side plate. Further, the pins may havea tapered portion between the shaft portion and a rear end thereof. Inthis case, the angle of inclination for the tapered portion ispreferably 30° or less relative to the outer circumferential surface ofthe pin, and the boundary between the rear end of the pin and the shaftportion is preferably chamfered in an arcuate shape along the axialdirection of the pin.

Further, the pins may have a surface hardening layer at the surfacelayer of the shaft portion and, assuming the entire length of the pin asL₁, the axial length between the two ends of the pin as L₂, and theregion for forming the surface hardening layer in the axial direction ofthe pin as L₃, they are preferably defined as: L₂−2>L₃>L₁−2L₂. Further,assuming the region for forming the surface hardening layer in the axialdirection of the pin as L₃ and the thickness of the annular side plateas T, it is preferred that they are defined as: L₁−2T>L₃>L₁−2L₂.

In this case, the surface hardening layer is preferably formed bycontrolling an RF current supplied to RF induction heating coils usedupon RF quenching the circumferential surface of the pin, or a relativemoving speed of the RF induction heating coils to the pin separately forboth ends of the pin and other portions.

Further, a cage for use in a roller bearing according to a secondinvention comprises a plurality of pins for rotatably supporting rollingelements of a roller bearing, a pair of annular side plates forretaining, by way of the pins, the rolling elements each at an equaldistance in the circumferential direction of a bearing ring, and aplurality of bushes each having, at a central portion, a tapered holefor fitting with a tapered portion formed at one end of the pins inwhich fitting holes for fitting with the bushes are formed to at leastone annular side plate of the pair of annular side plates, whereinfitting between the bushes and the fitting holes is applied asinterference fit for 5 μm or more.

According to the cage for use in the roller bearing according to theinventions in claims 1 to 3, 8 and 18, since the joining strengthbetween the pins and the annular side plate can be ensured withoutconstituting the weld portions for the pins and the annular side plateas in the existent weld portions, this can prevent concentration ofstress to the weld portions for the pins and the annular side plate oroccurrence of cracking, etc. Further, this can also prevent occurrenceof fretting or the like to the fitted portions between the pins and thepin-receiving holes.

According to the cage for use in the roller bearing of the inventions inclaims 4 and 5, the axial length of the rolling element can be ensuredlonger than that in the existent case in addition to the effectdescribed above.

According to the cage for use in the roller bearing of the inventions inclaims 6 and 7, occurrence of scraping can be prevented upon fitting theends of the pins into the pin-receiving holes of the annular side platein addition to the effects described above.

According to the cage for use in the roller bearing of the invention inclaim 9, since the pins can be fit from one direction into thepin-receiving holes formed in the annular side plate, the cage can beassembled easily.

According to the cage for use in the roller bearing of the inventions inclaims 10 to 17, occurrence of burrs can be prevented upon fitting theends of the pins into the pin-receiving holes of the annular side platein addition to the effects described above.

According to the cage for use in the roller bearing of the inventions inclaims 19 and 20, since large wear at the end of the pin due to contactwith a rolling element can be suppressed even when the rolling elementmoves greatly toward the annular side plate during use, the mechanicalstrength of the pin against the bending strength can be improved.Further, wear of the pin by fretting in the fitting portion between theannular side plate and the pin can be suppressed and occurrence ofabnormal wear that may possibly form trigger points for stressconcentration to the pin can be prevented.

According to the cage for use in the roller bearing of the invention inclaim 21, a surface hardening layer of a uniform depth can be formed tothe circumferential surface of the pin even when the outer diameter isdifferent between the central portion and the both ends of the pin.

According to the cage for use in the roller bearing of the invention inclaim 22, since the joining strength between the bush and the annularside plate can be ensured without constituting the weld portion for thebush and the annular side plate as in the existent weld portion,occurrence of stress concentration to the weld portion for the bush andthe annular side plate can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view showing a portion of a cage for use ina roller bearing according to a first embodiment of the presentinvention.

FIG. 2 is II-II cross sectional view of FIG. 1.

FIG. 3 is a side elevational view showing a portion of a cage for use ina roller bearing according to a second embodiment of the presentinvention.

FIG. 4 is IV-IV cross sectional view of FIG. 3.

FIG. 5 is a side elevational view showing a portion of a cage for use ina roller bearing according to a third embodiment of the presentinvention.

FIG. 6 is VI-VI cross sectional view of FIG. 5.

FIG. 7 is a view showing a fitted portion between a pin and apin-receiving hole.

FIG. 8 is a plane view for a weld portion shown in FIG. 7.

FIG. 9 is a view showing an example of a fitting method of a pin in acase where the hole diameter for each pin-receiving hole perforated inleft and right annular side plates is of an identical hole diameter.

FIG. 10 is an explanatory view for explaining the function and theeffect of the cage for use in the roller bearing according to the thirdembodiment of the present invention.

FIG. 11 is a fragmentary cross sectional view of the roller bearing cageshown in FIG. 5.

FIG. 12 is a fragmentary cross sectional view of a roller bearing cageaccording to a fourth embodiment of the present invention.

FIG. 13 is a view showing a weld portion in a case of welding a pin andan annular side plate by using a welding wire.

FIG. 14 is a fragmentary cross sectional view of a roller bearing cageaccording to a fifth embodiment of the present invention.

FIG. 15 is a side elevational view of a pin shown in FIG. 14.

FIG. 16 is a view showing a top end of a pin.

FIG. 17 is a view showing a rear end of a pin.

FIG. 18 is a fragmentary cross sectional view of a annular side plate onthe side where the top end of the pin is fitted.

FIG. 19 is a view for explaining the fitting direction of a pin in acase of assembling the cage shown in FIG. 14.

FIG. 20 is a fragmentary cross sectional view of a roller bearing cageaccording to a sixth embodiment of the present invention.

FIG. 21 is a fragmentary cross sectional view of a roller bearing cageaccording to a seventh embodiment of the present invention.

FIG. 22 is a side elevational view of a pin shown in FIG. 21.

FIG. 23 is a view showing the top end of the pin.

FIG. 24 is a view showing the rear end of the pin.

FIG. 25 is a fragmentary cross sectional view of a annular side plate onthe side where the top end of the pin is fitted.

FIG. 26 is a view for explaining the fitting direction of the pin in acase of assembling the cage shown in FIG. 21.

FIG. 27 is a view showing a test apparatus used for a fatigue strengthtest of a pin-type cage.

FIG. 28 is a graph showing the result of the fatigue strength test ofthe pin-type cage.

FIG. 29 is a graph showing bending curves of structural alloy steelsunder rotation.

FIG. 30 is a fragmentary cross sectional view of a roller bearing cageaccording to an eighth embodiment of the present invention.

FIG. 31 is a view for explaining a method in a case of forming an RFquenched layer to the circumferential surface of the pin shown in FIG.30.

FIG. 32 is a fragmentary cross sectional view of a roller bearing cageaccording to a ninth embodiment of the present invention.

FIG. 33 is a view showing an embodiment of applying the presentinvention to a cylindrical roller bearing.

FIG. 34 is a view showing an embodiment of applying the presentinvention to a radial self-aligning roller bearing.

FIG. 35 is a view showing an embodiment of applying the presentinvention to a thrust self-aligning roller bearing.

FIG. 36 is a view showing an embodiment of applying the presentinvention to a thrust cylindrical roller bearing.

FIG. 37 is a view showing an embodiment of applying the presentinvention to a thrust tapered roller bearing.

FIG. 38 is a fragmentary cross sectional view of a roller bearing cageaccording to a tenth embodiment of the present invention.

FIG. 39 is a view for explaining a step of fitting a pin of a cage intoa pin-receiving hole of an annular side plate.

FIG. 40 is a view for explaining the step of caulking a smalldiametrical shaft portion of a pin fitting into a pin-receiving hole ofan annular side plate.

FIG. 41 is a fragmentary cross sectional view of a roller bearing cageaccording to an eleventh embodiment of the present invention.

FIG. 42 is a view for explaining a step of fitting a pin of a cage intoa pin-receiving hole of an annular side plate.

FIG. 43 is a view for explaining a step of forming a tap hole to the endface of a pin fitting into the pin-receiving hole of an annular sideplate.

FIG. 44 is a fragmentary cross sectional view of a roller bearing cageaccording to a twelfth embodiment of the present invention.

FIG. 45 is a fragmentary cross sectional view of a roller bearing cageaccording to a twelfth embodiment.

FIG. 46 is a view showing an example of a welding torch used uponwelding a pin and an annular side plate.

FIG. 47 is a view for explaining a method of cold fitting a pin into apin-receiving hole of an annular side plate.

FIG. 48 is a view for explaining a method of shrink fitting apin-receiving hole of an annular side plate to a pin.

FIG. 49 is a view showing an example of an existent pin-type cage.

FIG. 50 is a view showing another example of an existent pin-type cage.

BEST MODE FOR PRACTICING THE INVENTION

Embodiments of the present invention are to be described with referenceto the drawings.

A cage for use in a roller bearing according to a first embodiment ofthe present invention comprises, as shown in FIG. 1 and FIG. 2, aplurality of pins 2 for rotatably supporting rolling elements 1 of acylindrical roller bearing and a pair of annular side plates 3, 3 forretaining the rolling elements 1, by way of the pins, each at anequal-distance in the circumferential direction of a bearing ring notillustrated.

The annular side plates 3, 3 are opposed to each other putting rollingelements 1 each formed into a cylindrical roller shape therebetween and,in the annular side plates 3, an annular side plate 3 on the left inFIG. 2 is formed with a plurality of threaded holes 5 in threadengagement with tapered threaded portions 12 each formed at one end ofthe pin 2 at a predetermined distance in the circumferential directionof the annular side plate 3.

On the other hand, a plurality of pin-receiving holes 4 are perforatedeach at a predetermined distance in the circumferential direction of theannular side plate 3 to the annular side plate 3 on the left in FIG. 2,and one end of the pin 2 on the side opposite to the threaded portion 12is fitting into each of the pin-receiving holes 4 by interference fitfor about 5 to 40 μm.

The end of the pin 2 fitting into the pin-receiving hole 4 is welded tothe annular side plate 3, and a weld portions 13 for the pins 2 and theannular side plate 3 are formed in a ring-shape substantially at aconstant welding width to the outer lateral surface of the annular sideplate 3 having the pin-receiving holes 4.

The pin 2 is formed of an iron and steel material such as SNCN 431,S35C, S38C, etc., and a carburized hardening layer 11 as a surfacehardening layer (refer to FIG. 7) is formed to the surface layer of eachpin 2. Further, a lubricant supply channel 26 is formed at the center ofthe pin 2 (refer to FIG. 2). The lubricant supply channel 26 haslubricant inlets 27 on both end faces, and a lubricant such as greaseflowing into the lubricant supply channel 26 from the lubricant inlets27 is discharged from a lubricant exit 28 formed to a central portion atthe outer circumferential surface of the pin 2. Further, a pin insertionhole 1 a is formed to the center of the rolling element 1 for passingthe pin 2.

As described above, since fitting between the pin 2 and thepin-receiving hole 4 is applied as interference fit for about 5 to 40μm, joining strength between the pin 2 and the annular side plate 3 canbe ensured without forming the weld portion for the pin 2 and theannular side plate 3 as in the weld portion shown in FIG. 49. Thus,since occurrence of stress concentration to the weld portion for the pin2 and the annular side plate 3 can be suppressed, this can preventoccurrence of cracking or the like to the weld portion for the pin 2 andthe annular side plate 3.

Further, since the cracking or the like to the weld portion caused bystress concentration can be prevented without forming the weld portionfor the pin 2 and the annular side plate 3 as in the weld portion (weldportion covering the entire end face of the pin) 6 shown in FIG. 49,lowering of stress by welding can be prevented. Further, TIG welding canbe used for the welding for the pin 2 and the annular side plate 3, andthis can decrease the residual tensile stress caused by welding. Whilewelding for the pin and the annular side plate is preferably TIG weldingor plasma welding, the current value can be lowered during welding alsoby MAG welding or the like and the residual stress can be decreased bycontrolling the gas flow rate during welding.

Then, a second embodiment of the present invention is to be describedwith reference to FIG. 3 and FIG. 4.

A cage for use in a rolling bearing according to the second embodimentof the invention comprises, as shown in FIG. 3 and FIG. 4, a pluralityof pins 2 for rotatably supporting rolling elements 1 of a cylindricalroller bearing, a pair of annular side plates 3, 3 for retaining therolling elements 1, by way of the pins 2, each at an equal distance in acircumferential direction of a bearing ring not illustrated, and aplurality of bushes 8 each having, at a central portion, a tapered holefor fitting a tapered portion 14 tapered toward the top end formed toone end of the pin 2, in which the annular plate 3 on the right in FIG.4 is formed with a plurality of fitting holes 7 for fitting the bushes8. The fitting holes 7 are formed each at a predetermined distance inthe circumferential direction of the annular side plate 3, and fittingbetween the bush 8 and the fitting hole 7 is applied as interference fitfor 5 μm or more and 40 μm or less. The annular side plate 3 on the leftin FIG. 4 is formed with a plurality of threaded holes 5 in threadengagement with tapered threaded portions 12 formed at one end of thepin 2 each at a predetermined distance in the circumferential directionof the annular side plate 3.

The bush 8 is welded to the annular side plate 3 and a weld portion 15with the bush 8 is formed in a ring shape substantially at a constantwelding width to the outer lateral surface of the annular side plate 3having the fitting hole 7. Further, the pin 2 is welded to the bush 8,and a weld portion 16 with the pin 2 is formed in a ring-shapesubstantially at a constant welding width to the outer end face of thebush 8.

As described above, since fitting between the fitting hole 7 formed inthe annular side plate 3 and the bush 8 is applied as an interferencefit for 5 μm or more and 40 μm or less, joining strength between theannular side plate 3 and the bush 8 can be ensured without forming theweld portion 15 between the annular side plate 3 and the bush 8 as inthe weld portion shown in FIG. 50, and occurrence of stressconcentration to the weld portion for the annular side plate 3 and thebush 8 can be suppressed.

Further, since the cracking or the like to the weld portion caused bystress concentration can be prevented without forming the weld portionfor the annular side plate 3 and the bush 8 and for the bush 8 and thepin 2 as in the weld portion shown in FIG. 50, lowering of the stresscaused by welding can be prevented. Further, the weld portion for thepin 2 and the annular side plate 3 can be formed by TIG welding(possibly also by plasma welding or the like), and this can decrease theresidual tensile stress caused by welding.

Then, a third embodiment of the present invention is to be describedwith reference to FIG. 5 to FIG. 10.

A cage for use in a roller bearing according to a third embodiment ofthe present invention comprises, as shown in FIG. 5 and FIG. 6, aplurality of pins 2 for rotatably supporting rolling elements 1 of acylindrical roller bearing and a pair of annular side plates 3, 3 forretaining the rolling elements 1 by way of the pins each at anequal-distance in the circumferential direction of a bearing ring notillustrated. In each of the annular side plates 3, a plurality ofpin-receiving holes 4 that are fitted with fitting portions 17, 18formed on both ends of the pins 2 by interference fit for 5 μm to 40 μmrespectively are perforated. The pin-receiving holes 4 are perforatedeach at a predetermined distance in the circumferential direction of theannular side plate 3, and the surface for each of a pin-receiving holes4 is finished by lathing to a roughness of 1.2 μm Ra or less. Thesurface of the pin-receiving hole 4 may also be fabricated beingfinished by girding or like other method in the same manner as for theend of the pin 2.

Then, assuming the outer diameter of the fitting portion 17 formed toone end of the pin 2 as d₁, and an outer diameter of the fitting portion18 formed to the other end of the pin 2 as d₂, the outer diameter forthe fitting portion 17, 18 are is defined as: d₁>d₂. Further, assumingthe outer diameter of the pin 2 as d₃, the outer diameter for thefitting portion 17, 18 is defined as: d₃>d₁>d₂.

The fitting portions 17, 18 are formed each into a cylindrical shape andthe outer circumferential surface of the fitting portion 17, 18 formingthe ends of the pin is finished by grinding. Further, the fittingportions 17 and 18 are welded respectively to the annular side plate 3,and weld portions 19, 20 with the fitting portions 17, 18 are formedeach in a ring-shape substantially at a constant welding width to theouter lateral surface of the annular side plate 3 as shown in FIG. 8.

In this case, the weld portions 19, 20 for the fitting portions 17, 18and the annular side plate 3 are formed by TIG welding or plasma weldingfor the pins 2 and the annular side plate 3 in which the extensionamount of the weld portions 19, 20 relative to the outer lateral surfaceof the annular side plate 3 is 0.5 mm or less.

The pin 2 is formed of an iron and steel material such as SNCM431, S35C,S38C, etc. and a carburized hardening layer 11 as a surface hardeninglayer is formed to the surface for each of the pins 2 as shown in FIG.7. A pin insertion hole 1 a is formed to the central portion of therolling element 1 for passing through the pin 2.

Like in the third embodiment described above, since fitting between thefitting portions 17, 18 formed to both ends of the pin 2 and thepin-receiving hole 4 formed in the annular side plate 3 is applied asinterference fit for about 5 μm to 40 μm, joining strength between thepin 2 and the annular side plate 3 can be ensured without forming theweld portions 19, 20 for the pin 2 and the annular side plate 3 as inthe weld portion shown in FIG. 49. Accordingly, even when a load in therotational direction (circumferential direction) exerts on the pin,occurrence of stress concentration to the weld portion for the pin andthe annular side plate can be suppressed.

Further, since the cracking or the like to the weld portion caused bystress concentration can be prevented without forming the weld portions19, 20 for the fitting portions 17, 18 and the annular side plate 3 asin the weld portion (weld portion covering the entire end face of thepin) 6 shown in FIG. 49, lowering of stress caused by welding can beprevented. Further, TIG welding can be used for the welding for the pin2 and the annular side plate 3, and this can decrease the residualtensile stress caused by welding. While welding for the pin and theannular side plate is preferably TIG welding or plasma welding, thecurrent value can be lowered during welding also by MAG welding or thelike and the residual stress can be decreased by controlling the gasflow rate during welding.

Further, in the embodiment described above, the cage can be assembledeasily by defining the outer diameters d₁, d₂ of the fitting portions17, 18 as d₁>d₂, preferably, d₃>d₁>d₂ (d₃: pin outer diameter). That is,in a case where the outer diameter for the fitting portions 17, 18 ismade as an identical diameter, fitting directions of the fittingportions 17, 18 to the pin-receiving hole 4 are contrary to each otherin the direction as shown in FIG. 9. However, by defining the outerdiameters d₁, d₂ of the fitting portions 17, 18 as: d₁>d₂, since thefitting directions of the fitting portions 17, 18 can be made identicalas shown in FIG. 10, the cage can be assembled easily.

Further, in the third embodiment, since the outer circumferentialsurface of the fitting portions of 17, 18 is finished by grinding,occurrence of scraping can be prevented upon fitting the fittingportions 17, 18 into the pin-receiving holes 4 of the annular side plate3. Further, since the weld portions 19, 20 for the pins 2 and theannular side plate 3 are formed by TIG welding or plasma welding in theembodiment described above, the extension amount of the weld portions19, 20 can be suppressed than usual. Furthermore, since the extensionamount of the weld portions 19, 20 relative to the outer lateral surfaceof the annular side plate 3 is made to 0.5 mm or less, the axial lengthof the rolling element 1 can be ensured to be longer than in theexistent case.

In the third embodiment described above, while the end face of the pin 2and the outer lateral surface of the annular plate 3 are formed on oneidentical plane, the end face 2 a of the pin 2 may be protruded from theouter lateral surface 3 a of the annular plate 3 within a range of 0.5mm or less as shown in FIG. 11. Alternatively, as shown in FIG. 12, theouter lateral surface 3 a of the annular plate 3 may be protrudedrelative to the end face 2 a of the pin 2 within a range of 0.5 mm orless.

Further, in the third embodiment, while the weld portions 19, 20 for thepin 2 and the annular side plate 3 are formed by method of directlywelding base materials to each other without using a welding wire, theweld portions 19, 20 for the pin 2 and the annular side plate 3 may beformed also by using a welding wire as shown in FIG. 13.

Then, a fourth embodiment of the present invention is to be describedwith reference to FIG. 14 to FIG. 19.

A cage for use in a roller bearing according to the fourth embodiment ofthe present invention comprises, as shown in FIG. 14, a plurality ofpins 2 for rotatably supporting rolling elements 1 of a cylindricalroller bearing and a pair of annular side plates 3, 3 for retaining therolling elements 1 by way of the pins each at an equal-distance in thecircumferential direction of a bearing ring not illustrated. In each ofthe annular side plates 3, a plurality of pin-receiving holes 4 that arefitted with cylindrical fitting portions 17, 18 formed on both ends ofthe pin 2 by interference fit for 5 μm to 40 μm are perforated. Thepin-receiving holes 4 are perforated to the annular side plate 3 each ata predetermined distance in the circumferential direction of the annularside plate 3, and the surface for each of the pin-receiving holes 4 isfinished by lathing to a roughness of 1.2 μm Ra or less.

Then, assuming the outer diameter of the fitting portion 17 formed toone end of the pin 2 as d₁, and an outer diameter of the fitting portion18 formed to the other end of the pin 2 as d₂, the outer diameters forthe fitting portions 17, 18 are defined as: d₁>d₂. Further, assuming theouter diameter of the pin 2 as d₃, the outer diameters for the fittingportions 17, 18 are defined as: d₃>d₁>d₂.

The fitting portions 17, 18 are welded respectively to the annular sideplate 3, and weld portions for the fitting portions 17, 18 and theannular side plate 3 are formed in a ring shape substantially at aconstant welding width to the outer lateral surface of the annular plate3.

The pin, as shown in FIG. 15, has a shaft portion 2 c between thefitting portion 17 and the fitting portion 18. The shaft portion 2 c isformed into a smaller diameter than the rear end (fitting portion 18) ofthe pin 2, and a tapered portion 21 (referrer to FIG. 17) is formedbetween the rear end (fitting portion 18) and the shaft portion 2 c ofthe pin 2 at an angle of inclination θ₂ of 30° or less relative to thecircumferential surface of the pin 2.

The top end of the pin 2 (fitting portion 17) is formed to a largerdiameter than the shaft portion 2 c and a chamfered portion 22 (refer toFIG. 16) is formed at the top end face of the pin 2 at an angle ofinclination θ₁ of 30° or less relative to the circumferential surface ofthe pin 2. A chamfered portion 23 (refer to FIG. 18) is formed to thepin-receiving hole 4 in which the top end of the pin 2 is fitted forreducing the frictional resistance with the pin 2. Further, the boundarybetween the chamfered portion 23 formed to the top end face of the pin 2and the top end of the pin 2 is chamfered in an arcuate shape with aradius of curvature of R along the axial direction of the pin 2 as shownin FIG. 16, and the boundary between the rear end of the pin 2 and thetapered portion 21 is chamfered in an arcuate shape at a radius ofcurvature of R along the axial direction of the pin 2.

In the fourth embodiment constituted as described above, since fittingbetween the fitting portions 17, 18 formed on both ends of the pin 2 andthe pin-receiving holes 4 formed in the annular side plate 3 is appliedas interference fit for about 5 μm to 40 μm, joining strength betweenthe pin 2 and the annular side plate 3 can be ensured without formingthe weld portion for the pin 2 and the annular side plate 3 as in theweld portion shown in FIG. 4. Accordingly, even when a load in therotational direction (circumferential direction) exerts on the pin,occurrence of stress concentration to the weld portion for the pin andthe annular side plate can be suppressed.

Further, in the forth embodiment described above, since the outerdiameters d₁, d₂ for the fitting portions 17, 18 are defined as: d₁>d₂,preferably, d₃>d₁>d₂ (d₃; outer diameter of pin), the cage can beassembled easily like the third embodiment. Further, since the chamferedportion 22 having an angle of inclination of 30° or less relative to thecircumferential surface of the pin 2 is disposed to the top end face ofthe pin 2, the top end of the pin 2 can be easily fitted to thepin-receiving hole 4 of the annular side plate 3, and the cage can beassembled easily. Further, since the boundary between the chamferedportion 22 formed to the top end face of the pin 2 and the top end ofthe pin 2 is chamfered in an arcuate shape with a radius of curvature ofR along the axial direction of the pin 2, occurrence of burrs, etc. canbe prevented upon fitting the top end of the pin 2 into thepin-receiving hole 4 of the annular side plate 3.

Further, in the fourth embodiment, since the rear end of the pin 2 canbe fitted easily into the pin-receiving hole 4 of the annular side plate3 by disposing the tapered portion 21 having the angle of inclination of30° or less relative to the circumferential surface of the pin 2 betweenthe rear end (fitting portion 18) and the shaft portion 2 c of the pin2, the cage can be assembled easily. Further, since the boundary betweenthe rear end and the tapered portion 21 of the pin 2 is chamfered in anarcuate shape at a radius of curvature of R along the axial direction ofthe pin 2, occurrence of burrs, etc. can be prevented upon fitting therear end of the pin 2 into the pin-receiving hole 4 of the annular sideplate. Further, since the surface roughness of the pin-receiving hole 4is decreased to 1.2 μm Ra or less, occurrence of burrs, etc. can beprevented upon fitting the both ends of the pin 2 into the pin-receivingholes 4.

In the fourth embodiment described above, while the outer diameter d₁ ofthe fitting portion 17 formed at one end of the pin 2 and the outerdiameter d₂ of the fitting portion 18 formed at the other end of the pin2 are defined as: d₁>d₂, the outer diameter d₁ of the fitting portion 17formed at one end of the pin 2 and the outer diameter d₂ of the fittingportion 18 formed at the other end of the pin 2 may also be defined as:d₁>d₂ like in a fifth embodiment shown in FIG. 20. However, thedirection of fitting the pin 2 is in the direction opposite to that inthe fourth embodiment.

Then, a sixth embodiment of the present invention is to be describedwith reference to FIG. 21 to FIG. 26.

A cage for use in a roller bearing according to a sixth embodiment ofthe present invention comprises, as shown in FIG. 21, a plurality ofpins 2 for rotatably supporting rolling elements 1 of a cylindricalroller bearing and a pair of annular side plates 3, 3 for retaining therolling elements 1 by way of the pins each at an equal-distance in thecircumferential direction of a bearing ring not illustrated. In each ofthe annular side plates 3, a plurality of pin-receiving holes 4 that tobe fitted with cylindrical fitting portions 17, 18 formed on both endsof the pin 2 by interference fit for 5 μm to 40 μm are perforated.

Then, assuming the outer diameter of the fitting portion 17 formed toone end of the pin 2 as d₁, and an outer diameter of the fitting portion18 formed to the other end of the pin 2 as d₂, the outer diameters forthe fitting portions 17, 18 are defined as: d₁>d₂. Further, assuming theouter diameter of the pin 2 as d₃, the outer diameters for the fittingportions 17, 18 are defined as: d₃>d₁>d₂.

The fitting portions 17, 18 are welded respectively to the annular sideplate 3, and weld portions for the fitting portions 17, 18 and theannular side plate 3 are formed in a ring shape substantially at aconstant welding width to the outer lateral surface of the annular plate3.

The pin-receiving holes 4 are perforated to the annular side plate 3each at a predetermined distance in the circumferential direction of theannular side plate 3 and the surface of each of the pin-receiving holes4 is finished by lathing to a roughness of 1.2 μm Ra or less.

The direction of fitting the pin 2 into the annular side plate 3 isshown in FIG. 26. As shown in the drawing, the cage for use in theroller bearing according to the sixth embodiment is assembled by fittingthe pin 2 into the pin-receiving hole 4 formed in the annular side plate3 in the direction of an arrow in the drawing, and a chamfered portion22 (refer to FIG. 23) is formed at an angle of inclination of θ₁ of 30°or less relative to the circumferential surface of the pin 2 at the topend face of the pin 2 to be fitting into the pin-receiving hole 4.

As shown in FIG. 22, the pin 2 has a shaft portion 2 c between thefitting portion 17 and the fitting portion 18. The shaft portion 2 c isformed to a smaller diameter than the rear end (fitting portion 18) ofthe pin 2, and a tapered portion 21 (refer to FIG. 24) is formed betweenthe rear end (fitting portion 18) and the shaft portion 2 c of the pin 2at an angle of inclination θ₂ of 30° or less relative to thecircumferential surface of the pin 2.

The boundary between the chamfered portion 22 formed at the top end faceof the pin 2 and the top end of the pin 2 is chamfered as shown in FIG.23 in an arcuate shape at a radius of curvature of R along the axialdirection of the pin 2. Further, the boundary between the rear end andthe tapered portion 21 of the pin 2 is chamfered, as shown in FIG. 24,into an arcuate shape at the radius of curvature of R along the axialdirection of the pin 2. A chamfered portion 23 (referred to 25) isformed to the pin-receiving hole 4 into which the top end of the pin 2is fitted in order to reduce the frictional resistance with the pin 2.

In the sixth embodiment constituted as described above, since the outerdiameters d₁, d₂ of the fitting portions 17, 18 are defined as: d₁>d₂,preferably, d₃>d₁>d₂ (d₃: outer diameter of pin), the cage can beassembled easily like the third to sixth embodiments. Further, since thetop end of the pin 2 can be fitted easily into the pin-receiving hole 4of the annular side plate 3 by forming the chamfered portion 22 havingthe angle of inclination of 30° or less relative to the circumferentialsurface of the pin 2 to the top end face of the pin 2, the cage can beassembled easily. Further, since the boundary between the chamferedportion 22 formed to the top end face of the pin 2 and the top end ofthe pin 2 is chamfered into an arcuate shape at a radius of curvature ofR along the axial direction of the pin 2, occurrence of burrs, etc. canbe prevented upon fitting the top end of the pin 2 into thepin-receiving hole 4 of the annular side plate 3.

Further, in the sixth embodiment, since the rear end of the pin 2 can befitted easily into the pin-receiving hole 4 of the annular side plate 3by forming the tapered portion 21 having the angle of inclination of 30°or less relative to the circumferential surface of the pin 2 between therear end (fitting portion 19) and the shaft portion 2 c of the pin 2,the cage can be assembled easily. Further, since the boundary betweenthe rear end and the tapered portion 21 of the pin 2 is chamfered in thearcuate shape at the radius of curvature of R along the axial directionof the pin 2, occurrence of burrs, etc. can be prevented upon fittingthe rear end of the pin 2 into the pin-receiving hole 4 of the annularside plate. Further, since the surface roughness of the pin-receivinghole 4 is decreased to 1.2 μm Ra or less, occurrence of burrs, etc. canbe prevented upon fitting the both ends of the pin 2 into thepin-receiving holes 4.

Further, occurrence of burrs can be prevented upon fitting the both endsof the pin 2 into the pin-receiving hole 4 by decreasing the surfaceroughness of the pin-receiving hole of to 1.2 μm Ra or less.

The present inventors conducted a fatigue strength test for the pin-typecage by using test samples of the specification shown in Table 1 inorder to confirm the effect of the cage for use in the roller bearingaccording to the present invention. Specifically, each of the testsamples in Table 1 was set to a test apparatus shown in FIG. 27 (ServoPulser EH-15 manufactured by Simazu Seisakusho) and a both-directiontest at 20 Hz was conducted under a predetermined test load (stress).TABLE 1 Comparative Comparative Example 1 Example 2 Example 1 Example 2Example 3 Pin structure 2-stage pin Tapered bush Straight StraightTapered bush Gap 0.1 to 0.2 mm 0 mm — — Interference — 0 to 5 μm 13 to18 μm Control for driving amount Welding range Buried in side Buried inside Only on Only on On two plate hole plate hole circumferencecircumference circumferences

FIG. 28 shows the test result of the fatigue strength test describedabove. From the test result in the figure, it was confirmed thatExamples 1 to 3 of the present invention were improved in the fatiguestrength compared with Comparative Example 1 and Comparative Example 2and it reached as far as the fatigue strength of the base material forthe pin shown in FIG. 29. Since fretting, etc. are liable to occur tothe fitting portion between the pin 2 and the pin-receiving hole 4 in acase of setting the lower limit value for the interference of thepin-receiving hole 4 to the pin 2 to less than 5 μm, the lower limitvalue for the interference was set to 5 μm. Further, since an excessfitting force was required and scraping occurred upon fitting the pin 2into the pin-receiving hole 4 as shown in Table 2 when setting the upperlimit value for the interference of the pin-receiving hole 4 to the pin2 to 41 μm or more, and scraping or burrs occurred at an interference of40 μm or more, the upper limit value for the interference was set to 40μm. TABLE 2 Surface pressure by fitting and example of calculation forfitting force${{Average}\quad{surface}\quad{pressure}\text{:}\quad{pm}} = {\frac{E}{2}\frac{\Delta\mathbb{d}}{\mathbb{d}}\frac{( {1 - k^{2}} )( {1 - {k_{0}}^{2}} )}{1 - {k^{2}{k_{o}}^{2}}}}$Fitting force: F = μ · pm · π · d · B μ = 0.12 Calculation CalculationCalculation Calculation Calculation Calculation Calculation Example 1Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 d: shaft12.6 12.6 12.6 12.6 12.6 12.6 12.6 diameter (mm) B: width (mm) 16 16 1616 16 16 16 Δd: Effective 0.005 0.01 0.015 0.02 0.025 0.030 0.040interference (mm) E: young's 207760 207760 207760 207760 207760 207760207760 modulus Side plate width 35 35 35 35 35 35 35 (mm) k: thicknessratio 0.36 0.36 0.36 0.36 0.36 0.36 0.36 Ko: pin pore ratio 0 0 0 0 0 00 Pm: average 35.879 71.756 107.643 143.521 179.399 215.268 287.024surface pressure (N/mm) μ: friction 0.120 0.120 0.120 0.120 0.120 0.1200.120 coefficient F: fitting force 2726.92 5453.84 8180.76 10907.6613634.58 16361.52 21815.36 (N) upon pin fitting Number of pins 27 27 2727 27 27 27 Total press load 73627.4 147254.8 220882.2 294509.6 368137441761 589014 (N) upon fitting into side plate

FIG. 30 shows an embodiment of applying the present invention to apin-type cage used for a tapered roller bearing. As shown in thedrawing, the pin-type cage according to this embodiment comprises aplurality of pins 2 (only one of them is illustrated in the drawings)for rotatably supporting rolling elements 1 of the tapered rollerbearing and a pair of annular side plates 3, 3 for retaining the rollingelements 1 each at an equal distance in the circumferential direction ofa bearing ring (not illustrated) by way of the pins 2. A plurality ofpin-receiving holes 4 are perforated in each of the annular side plates3 that fit with cylindrical fitting portions 17, 18 formed at both endsof the pins 2 by insert fit for 5 μm to 40 μm.

The pin 2 has a shaft portion 2 c that is inserted through a pininsertion hole 1 a formed in the central portion of the rolling element1. The shaft portion 2 c is formed to a smaller diameter than thefitting portions 17, 18 formed at both ends of the pin 2, and a taperedportion 21 is formed at an angle of inclination of 30° or less relativeto the circumferential surface of the pin 2 between the fitting portion18 formed at one end of the pin 2 and the shaft portion 2 c.

Further, pin 2 is formed of an iron and steel material such as SNCM431,S35C, and S38C, and a RF quenched layer 24 is formed as a surfacehardening layer to the circumferential surface of each pin. The RFquenched layer 24 is formed to the circumferential surface of the pin 2so as to satisfy the relation: L₁>L₃>L₁−2L₂, preferably, L₁−2T>L₃>L₁−2L₂assuming the entire length of the pin 2 as L₁, the axial length of thefitting portions 17, 18 as L₂, the region forming the RF quenched layer24 in the axial direction of the pin 2 as L₃, and the thickness of theannular side plate 3 as T.

The RF quenched layer 24 is present also on both ends of the pin 2(fitting portions 17, 18) fitting into the pin-receiving holes 4 of theannular side plates 3 by defining the region L₃ forming the RF quenchedlayer 24 in the axial direction of the pin 2 as: L₁>L₃>L₁−2L₂,preferably, L₁−2T>L₃>L₁−2L₂. Since this can suppress large wear at theends of the pin 2 by the rolling element 1 even when the rolling element1 moves toward the annular side plate and is in contact with the end ofthe pin 2 during use, the mechanical strength of the pin 2 to thebending stress can be increased.

FIG. 31 is a view showing an example in a case of forming the RFquenched layer 24 to the circumferential surface of the pin 2. As shownin the drawing, in a case of forming the RF quenched layer 24 to thecircumferential surface of the pin 2, an RF current supplied to RFinduction heating coils 25 or a relative moving speed of the RFinduction heating coils 25 to the pin 2 used when conducting RFquenching to the circumferential surface of the pin 2 is controlledseparately for the both ends of the pin 2 (fitting portions 17, 18) andfor other portions.

As described above, by controlling the RF current supplied to the RFinduction heating coils 25 or the relative moving speed of the RFinduction heating coils 25 to the pin 2 separately for both ends of thepin 2 (fitting portions 17, 18) and for other portions when forming theRF quenched layer 24 as the surface hardening layer to thecircumferential surface of the pin 2, the RF quenched layer 24 ofuniform quenching depth can be formed to the circumferential surface ofthe pin 2 even in a case where the outer diameter is different betweenthe central portion and both ends of the pin 2.

The present invention is not restricted to the embodiment describedabove. For example, while the tapered portion 21 is formed between therear end (fitting portion 18) and the shaft portion 2 c of the pin 2 inthe seventh embodiment shown in FIG. 30, a tapered portion 21 may alsobe formed between a fitting portion 17 formed at the other end of thepin 2 and the shaft portion 2 c as shown in the eighth embodiment shownin FIG. 32. Further, while the case of applying the present invention tothe pin-type cage of the tapered roller bearing is exemplified in theseventh and eighth embodiments, the present invention is applicable alsoto a cylindrical roller bearing as shown in FIG. 33, or a self-aligningroller bearing as shown in FIG. 31. Further, while an example ofapplying the present invention to a pin-type cage for the radial rollerbearing is exemplified in each of the embodiment shown in FIG. 30, FIG.32 to FIG. 34, the present invention is applicable, for example, also toa thrust self-aligning roller bearing as shown in FIG. 35, a thrustcylindrical roller bearing as shown in FIG. 36, and a thrust taperedroller bearing as shown in FIG. 37.

Then, a ninth embodiment of the present invention is to be describedwith reference to FIG. 38 to FIG. 40.

A pin-type cage according to the ninth embodiment of the presentinvention comprises, as shown in FIG. 38, a plurality of pins 2 (onlyone of them is shown in the drawing) for rotatably supporting rollingelements 1 of a cylindrical roller bearing and a pair of annular sideplates 3, 3 for retaining the rolling elements 1 by way of the pins eachat an equal-distance in the circumferential direction of the bearingring (not illustrated). A plurality of pin-receiving holes 4 areperforated in each of annular side plates 3 for fitting the end of thepin 2 by interference fit for 5 μm to 40 μm.

Both ends of the pin 2 fitting into the pin-receiving hole 4 are weldedrespectively to the annular side plate 3, and weld portions 19, 20 forthe pin 2 and the annular side plate are formed each in a ring shapesubstantially at a constant welding width to the outer lateral surfaceof the annular side plate 3.

The rolling element 1 has a pin insertion hole 1 a for inserting the pin2 therethrough at an axial core portion, and a smaller shaft portion 29with a diameter smaller than the outer diameter of the pin 2 is formedcoaxially with the pin 2 at both ends of the pin 2 passing through thepin insertion hole 1 a.

In a case of assembling the pin-type cage as described above, a spacer30 for dimensional adjustment is at first attached at both ends of a pin2 protruding from both end faces of a rolling element 1 as shown in FIG.39 and then both ends of the pin 2 are fitting into a pin-receiving hole4 formed in an annular side plate 3. Then, as shown in FIG. 40, theouter lateral surface of the annular side plate 3 is plasticallydeformed into a concave shape by a caulking jig 31 and, after caulkingthe outer circumferential surface of the smaller diameter shaft portion29 formed to both ends of the pin 2, the both ends of the pin 2 and theannular side plates 3 are joined by welding.

As described above, since the fitting between the pin-receiving holes 4formed in the annular side plate 3 and the pin 2 is applied asinterference fit for about 5 μm to 40 μm, the joining strength betweenthe pin 2 and the annular side plate 3 can be ensured without formingthe weld portions 19, 20 for the pin 2 and the annular side plate 3 asin the weld portion shown in FIG. 4. Accordingly, even when a load inthe rotational direction (circumferential direction) exerts on the pin,occurrence of stress concentration to the weld portion for the pin andthe annular side plate can be suppressed.

Further, since the smaller diameter shaft portion 29 of a diametersmaller than the outer diameter of the pin 2 are disposed on both endsof the pin 2, a portion of the annular side plate 3 can easily bedeformed plastically by the caulking jig 31 upon caulking both ends ofthe pin 2 fitting into the pin-receiving hole 4 of the annular sideplate 3 by the caulking jig 31 shown in FIG. 40. Accordingly, the pin 2can be fixed firmly to the annular side plate 3 even when the pin 2 andthe pin-receiving hole 4 are fitted by interference fit for 40 μm to 60μm.

Then, a tenth embodiment of the present invention is to be describedwith reference to FIG. 41 to FIG. 43.

A pin-type cage for use in a roller bearing according to the tenthembodiment of the present invention comprises, as shown in FIG. 41, aplurality of pins 2 (only one of them is shown in the drawing) forrotatably supporting rolling elements 1 of a cylindrical roller bearingand a pair of annular side plates 3, 3 for retaining the rollingelements 1 by way of the pins each at an equal-distance in thecircumferential direction of the bearing ring (not illustrated). In eachof the annular side plates 3, a plurality of pin-receiving holes 4 thatare fitted with the ends of the pin 2 by interference fit for 5 μm to 40μm are perforated respectively.

Both ends of the pin 2 are welded respectively to the annular side plate3, weld portions 19, 20 for the pin 2 and the annular side plate areformed each in a ring shape substantially at a constant welding width tothe outer lateral surface of the annular side plate 3, and a settingscrew 30 for setting the pin 2 and the annular side plate 3 is screwedtherein.

In a case of assembling the pin-type cage as described above, both endsof the pin 2 protruding from the both end faces of the rolling element 1are at first fitting into the pin-receiving hole 4 formed in the annularside plate 3 as shown in FIG. 42. Then, as shown in FIG. 43, a tap hole31 is formed to both end faces of the pin fitting into the pin-receivinghole 4, and a setting screw 30 is screwed into the tap hole 31 to fixthe pin 2 and the annular side plate 3 and then both ends of the pin 2are joined by welding to the annular side plate 3.

As described above, since fitting between the pin-receiving holes 4formed in the annular side plate 3 and the pin 2 is applied asinterference fit for about 5 μm to 40 μm, joining strength between thepin 2 and the annular side plate 3 can be ensured without forming theweld portions 19, 20 for the pin 2 and the annular side plate 3 as inthe weld portion shown in FIG. 4. Accordingly, even when a load in therotational direction (circumferential direction) exerts on the pin,occurrence of stress concentration to the weld portion for the pin andthe annular side plate can be suppressed.

Then, an eleventh embodiment of the present invention is to be describedwith reference to FIG. 44 to FIG. 47.

A pin-type cage for use in roller bearing according to a eleventhembodiment of the present invention comprises, as shown in FIG. 41, aplurality of pins 2 (only one of them is shown in the drawing) forrotatably supporting rolling elements 1 of a cylindrical roller bearingand a pair of annular side plates 3, 3 for retaining the rollingelements 1 by way of the pins each at an equal-distance in thecircumferential direction of the bearing ring (not illustrated). In eachof the annular side plates 3, a plurality of pin-receiving holes 4 thatare fitted with the ends of the pin 2 by interference fit for 5 μm to 40μm are perforated respectively.

Both ends of the pin 2 fitting into the pin-receiving holes 4 are weldedrespectively to the annular side plate 3, and spot weld portions 32 withthe pin 2 are formed to the outer lateral surface of the annular sideplate 3 as shown in FIG. 45 by a welding torch 33 of a shape shown inFIG. 46.

The present inventors, et al. prepared a pin-type cage in which the pinsand the annular side plate were joined by spot welding (welding time:about 14 min) and a pin-type cage in which the pins and the annular sideplate were joined by an existent welding method (welding time: about 30min). Then, a tensile load and a compressive load (load applied: 1600kg) were repetitively loaded in a state of giving a sinusoidal wave at20 Hz to the pins of the pin-type cages to investigate the bearing lifeof tapered roller bearings (outer diameter: 650 mm, inner diameter: 400mm, width: 250 mm, number of rolling elements: 27, pin diameter: 12.6mm, cage outer diameter: 580 mm, cage inner diameter: 542 mm) till thebase material of the pin was fractured by fatigue. The result is shownin Table 3. TABLE 3 Life evaluation value Example 4 10 ComparativeExample 3 1 Comparative Example 4 12

In Table 3, Example 4 shows the life evaluation value for a taperedroller bearing in a case of joining the pin and the annular side plateby spot welding, Comparative Example 3 shows the life evaluation valuefor a tapered roller bearing in a case of not joining the pin and theannular side plate by welding, and Comparative Example 4 shows the lifeevaluation value for a tapered roller bearing in a case of joining thepin and the annular side plate by welding by an existent method,respectively.

As apparent from the test result shown in Table 3, it can be seen thatthe same extent of the bearing life as in the existent case can beobtained by joining the pin 2 and the annular plate 3 by spot welding.Accordingly, by joining the pin 2 and the annular side plate 3 by spotwelding, occurrence of stress concentration to the weld portion for thepin 2 and the annular side plate 3 can be prevented without greatlylowering the mechanical strength of the cage.

In a case of fitting the end of the pin 2 into the pin-receiving hole 4formed in the annular side plate 3, it is preferred to adopt a method ofcooling the end of the pin 2 and then fitting the end of the pin 2 intothe pin-receiving hole 4 (cold fit) as shown in FIG. 47, or a method ofheating the peripheral portion of the pin-receiving hole 4 and thenfitting the end of the pin 2 into the pin-receiving hole 4 (shrinkagefit) as shown in FIG. 48.

1. A cage for use in a roll bearing comprising a plurality of pins forrotatably supporting rolling elements of a roller bearing and a pair ofannular side plates for retaining, by way of the pins, the rollingelements each at an equal distance in the circumferential direction of abearing ring, in which pin-receiving holes fitting with one ends of thepins are formed to at least one annular side plate in the pair ofannular side plates, wherein fitting between the pins and thepin-receiving holes is applied as interference fit for 5 μm or more. 2.A cage for use in a roller bearing according to claim 1, wherein thefitting between the pins and the pin-receiving holes is applied asinterference fit for 5 μm or more and 40 μm.
 3. A cage for use in aroller bearing according to claim 1, wherein the ends of the pinsfitting into the pin-receiving holes are welded to the annular sideplate, the annular side plate has weld portions for the pins and theannular side plate at the outer lateral surface, and the weld portionsare formed into a ring shape substantially at a constant width.
 4. Acage for use in a roller bearing according to claim 3, wherein the weldportions are formed by TIG welding or plasma welding for the pin and theannular side plate.
 5. A cage for use in a roller bearing according toclaim 4, wherein the extension amount of the weld portions of theannular side plate relative to the outer lateral surface thereof iswithin 0.5 mm.
 6. A cage for use in a roller bearing according to claim1, wherein the ends of the pins fitted into the pin-receiving holes arefinished by grinding.
 7. A cage for use in a roller bearing according toclaim 1, wherein the pin-receiving holes have a surface roughness of 1.2μm or less.
 8. A cage for use in a roller bearing according to claim 1,wherein the pin-receiving holes are formed in both of the pair ofannular side plates.
 9. A cage for use in a roller bearing according toclaim 8, wherein one of the two ends of the pin is formed to a smallerdiameter than that of the other end.
 10. A cage for use in a rollerbearing according to claim 9, wherein the pins have a shaft portionpassing through a rolling element insertion hole formed in the axialcore of the rolling element and the two ends of the pin fitting into thepin-receiving holes are formed each to a larger diameter than that ofthe shaft portion.
 11. A cage for use in a roller bearing according toclaim 9, wherein the pins have a chamfered portion at the top end facethereof.
 12. A cage for use in a roller bearing according to claim 11,wherein the chamfered portion is formed at an angle of inclination of30° or less relative to the outer circumferential surface of the pin.13. A cage for use in a roller bearing according to claim 11, whereinthe chamfered portion is formed into an arcuate shape along the axialdirection of the pin.
 14. A cage for use in a roller bearing accordingto claim 10, wherein the pin-receiving holes have a chamfered portion atthe inner surface of the annular side plate.
 15. A cage for use in aroller bearing according to claim 10, wherein the pins have a taperedportion between the shaft portion and a rear end thereof.
 16. A cage foruse in a roller bearing according to claim 15, wherein the angle ofinclination for the tapered portion is 30° or less relative to the outercircumferential surface of the pin.
 17. A cage for use in a rollerbearing according to claim 15, wherein the boundary between the rear endand the shaft portion of the pin is chamfered in an arcuate shape alongthe axial direction of the pin.
 18. A cage for use in a roller bearingaccording to claim 10, wherein the pins have a surface hardening layerat a surface layer of the shaft portion.
 19. A cage for use in a rollerbearing according to claim 18, wherein it is defined as:L ₁ >L ₃ >L ₁−2L ₂ when assuming the entire length of the pin as L₁, theaxial length between the two ends of the pin as L₂, and the region forforming the surface hardening layer in the axial direction of the pin asL₃.
 20. A cage for use in a roller bearing according to claim 18,wherein it is defined as:L ₁−2T>L ₃ >L ₁−2L ₂ when assuming the region for forming the surfacehardening layer in the axial direction of the pin as L₃ and thethickness of the annular side plate as T.
 21. A cage for use in a rollerbearing according to claim 18, wherein the surface hardening layer isformed to the circumferential surface of the pin by controlling an RFcurrent supplied to RF induction heating coils used upon RF quenching ofthe circumferential surface of the pin, and a relative moving speed ofthe high frequency induction heating coils to the pin separately forboth ends of the pin and other portions.
 22. A cage for use in a rollerbearing comprising a plurality of pins for rotatably supporting rollingelements of a roller bearing, a pair of annular side plates forretaining, by way of the pins, the rolling elements each at an equaldistance in the circumferential direction of a bearing ring, and aplurality of bushes each having, at a central portion, a tapered holefitting to a tapered portion formed at one end of the pins in whichfitting holes fitting with the bushes are formed to at least one annularside plate of the pair of annular side plates, wherein fitting betweenthe bushes and the fitting holes is applied as interference fit for 5 μmor more.
 23. A cage for use in a roller bearing according to claim 2,wherein the ends of the pins fitting into the pin-receiving holes arewelded to the annular side plate, the annular side plate has weldportions for the pins and the annular side plate at the outer lateralsurface, and the weld portions are formed into a ring shapesubstantially at a constant width.
 24. A cage for use in a rollerbearing according to claim 10, wherein the pins have a chamfered portionat the top end face thereof.
 25. A cage for use in a roller bearingaccording to claim 12, wherein the chamfered portion is formed into anarcuate shape along the axial direction of the pin.
 26. A cage for usein a roller bearing according to claim 16, wherein the boundary betweenthe rear end and the shaft portion of the pin is chamfered in an arcuateshape along the axial direction of the pin.